1. Field of the Invention
The present invention relates to a numerical controller having a tool trajectory display function.
2. Description of the Related Art
Coordinate values of the tool center point are calculated from coordinate values of respective axes, and based on the calculated coordinated values, a shape of a machined surface is determined. Japanese Patent Application Laid-Open No. 9-69003 discloses a method for calculating a compensation vector for avoiding interference due to tool radius compensation. Further, Japanese Patent Application Laid-Open No. 63-257003 discloses a technique relating to calculating a tool radius compensation vector.
In a five-axis machining tool, it is possible to calculate coordinate values of a tool center point based on coordinate values of the respective axes, and to calculate a tool trajectory from the obtained coordinate values of the tool center point. However, due to the effect of the tool radius in actual machining, the shape of a trajectory of a tool center point 220 of a tool 22 such as a ball-end mill and that of a trajectory of an actual machining point do not match with each other, and the shape of the trajectory of the tool center point 220 and the shape of a machined surface of a workpiece do not always match with each other, as shown in FIG. 6.
In machining using a numerical controller, compensation is generally made considering the effect of the tool radius, and a trajectory that is more closer to the shape of a machined surface can be calculated by obtaining a tool radius compensation vector simultaneously with coordinate values of respective axes.
In actual machining, the shape of a trajectory of a tool center point and the shape of a machined surface do not match with each other due to the effect of the tool radius. While the trajectory of a tool center point can be calculated from coordinate values of the respective axes, it is disadvantageously difficult to calculate the shape of a machined surface.